A conveying assembly is shown in EP-B-2 818 050, which discloses a stationary guide element provided below and parallel to an overhead conveyor for the avoidance of rotation around an essentially vertical axis. Stops are mounted on a guide chain disposed generally horizontally below and essentially parallel to the overhead conveyor. A guide chain moves synchronously with the drive chain. The stops engage the shackles from which the poultry carcasses are suspended to prevent rotation of the shackles about the essentially horizontal rotation axis.
Such conveying assembly suffers from several drawbacks and disadvantages. For one the known conveying assembly is relatively complicated. Another drawback is that the stops engage the trailing part of the shackles as seen in the conveying direction. This is disadvantageous in view of the close proximity of adjacent shackles, wherein the shackle pitch is about 6 inch or 152.4 mm, whereas the outside shackle dimension is approximately 130 mm, leaving only 22.4 mm between adjacent shackles. In this narrow space the stops must be accurately positioned which is a hard task in a fast-moving shackle train. Accordingly the prior art conveying assembly is prone to misalignment, particularly when the approaching shackles are swinging.
Another disadvantage is that the guide chain usually moves around guide wheels, which causes—at the location of the outfeed near any such guide wheel—that the stops have difficulty to disengage from the shackles.
Yet another disadvantage is that even when the shackles are stabilized and prevented from rotation around a vertical and around a horizontal axis, this does not guarantee that also the poultry carcasses are prevented from such movements. The reason for that is that from a mechanical point of view a suspended poultry carcass can be modelled as a series of hinge points at ankle, knee and hip joint, that are interconnected by poultry bones.
U.S. Pat. No. 3,750,231 discloses a conveying assembly with shackles from which poultry is suspended by the legs. The shackles are positioned accurately by spaced blocks in an endless chain that is driven in the direction of product flow along the conveyor. The spaced blocks evenly space the shackles for properly receiving the carcasses.
U.S. Pat. No. 4,709,448 discloses a conveying in which the guide element is movable in the conveying direction and the stops are mounted on the guide element, wherein the guide element is provided below the shackles so as to arrange that the stops are able to engage the legs of the poultry carcasses suspended from the shackles. This feature avoids a separate stationary guide element for the avoidance of the rotation around an essentially vertical axis, by merging the functionality of this stationary guide element with the functionality of the moving stops that prevent rotation around an essentially horizontal axis. These functionalities are merged into a single movable guide element on which the stops are mounted. The feature of engaging the legs of the poultry carcasses arranges that rather than merely stabilizing the shackles, the poultry carcasses themselves are stabilized and prevented from rotation around either a vertical rotation axis or horizontal rotation axis. At the outfeed the stops are also better equipped to disengage from the poultry legs that are relatively flexible in comparison with the shackle material.